Proof load testing in the Netherlands - overview of current research
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Challenge the future
Delft University of Technology
Proof load testing in the Netherlands
Eva Lantsoght
Overview of current research
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Overview
• Introduction • Why proof loading?
• Existing guidelines?
• Pilot proof load tests • Laboratory experiments • Recommendations
• Preparation of proof load tests
• Execution of proof load tests
• Analysis of proof load tests
• Summary and conclusions Slab shear experiments, TU Delft
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Why load testing? (1)
Bridges from 60s and 70s
The Hague in 1959
Increased live loads
common heavy and long truck (600 kN)
End of service life + larger loads
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Safety philosphy of proof load testing
• Safety philosophy • Stop criteria:
• Further loading not permitted
• Failure near
• Irreversible damage near
MSc Thesis W. Vos
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Existing Guidelines for proof loading
• Europe: DAfStB Richtlinie • Originally derived for
buildings • Plain and reinforced
concrete • For flexure
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Existing Guidelines for proof loading
• North America: • Buildings: ACI 437.2M-13
• Bridges: Manual of Bridge
Rating Through Load
Testing (1998)
• ACI 437.2M-13: • Proof load testing load
combination
• Acceptance criteria for
flexure
• Cyclic loading protocol
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Research need
• Guideline for proof loading of existing RC slab bridges for the Netherlands
• Flexure + shear
• Measurements? Target proof load?
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TU Delft Proof Load Tests
• Proof load tests: • Heidijk 2007
• Medemblik 2009
• Vlijmen-Oost 2013
• Halvemaans Bridge 2014
• Ruytenschildt Bridge 2014
• Viaduct Zijlweg 2015
• Viaduct De Beek 2015
Load test to failure of Ruytenschildt Bridge, summer 2014
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Beam tests
• Ruytenschildt beams • Cyclic loading protocol
• Analysis of stop criteria
• Beams with plain bars
• Effect of number of cycles
• Effect of loading speed
• Load levels
• Analysis of stop criteria
Beams RSB01 after failure (Yang, 2015)
Yang, Y. (2015). "Experimental Studies on the Structural Behaviours of Beams from Ruytenschildt Bridge," Stevin Report 25.5-15-09, Delft University of Technology, Delft, 76 pp.
Beams RSB02B after failure (Yang, 2015)
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Preparation steps (1)
• Preliminary inspection and rating
• Determination of dimensions • Live load: EN 1991-2:2003 • RBK load levels
• Different β • Different load factors
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Preparation steps (2)
• Critical position • Bending moment: largest
moment
• Shear: 2.5d from support
• Required proof load • Same shear or bending
moment as with load
combination
• Value → considered safety
level
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Preparation steps (3)
• Sensor plan: • Deflection profiles in longitudinal
and transverse direction
• Deflection at supports
• Strain on bottom of cross-section
• Reference strain measurements to
correct for T
• Opening existing cracks
• Opening new cracks
• Applied load => load cells
• Acoustic emission measurements
(current research)
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Execution steps (1)
• Cyclic loading scheme • Acoustic emission measurements
• Check linearity and reproducibility of measurements
• Check residual deformations => no non-linearity
• Load levels ≈ safety levels CC3 RBK:
• Low level to check instrumentation
• SLS
• Intermediate level
• Target proof load
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Execution steps (2)
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Analysis Steps (1)
• Data analysis • Correct for T
• Correct for support
displacements
• Make final plots for report
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Discussion and future research
• Minimum measurements • “Quick and easy” method
for practice • Improvement of stop criteria
for shear
• Draft guidelines submitted to RWS in December
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Summary and conclusions
• Proof loading to approve existing bridges, also for shear
• Pilot proof load tests in the Netherlands + beam tests
• Current recommendations • First draft guidelines for practice
submitted
Viaduct Zijlweg